The present invention relates generally to an apparatus for removing trash or foreign matters contained in fibers in a spinning unit of an open-end spinning frame. More specifically, it relates to an apparatus for removing and transporting the trash with an improved efficiency without allowing the trash to be drawn back into the fibers and carried into a spinning rotor in the open-end spinning unit.
In a conventional open-end spinning unit as exemplified in FIG. 1 and designated generally by reference numeral 1, a sliver 3 introduced through a sliver inlet 2 is advanced by a feed roller 4 rotating in a direction to feed the sliver and a presser 5 operable in conjunction therewith to a cylindrical combing roller 6 which is rotatably disposed within a space formed in the spinning unit 1. The sliver 3 thus fed is opened or separated into individual fibers by the combing action of the rotating combing roller 6. The separated fibers are then transferred, while being combed by the combing roller 6, in the direction as depicted by an arrow along the circumferential surface of the combing roller 6 and introduced into a spinning rotor 11 through a fiber feed channel 10 under the influence of a current of air stream developed by vacuum which is created by rotation at an extremely high speed of the spinning rotor 11. The fibers are thereafter deposited in a fiber collecting groove formed at the outermost periphery in an annular form in the spinning rotor 11, and subsequently withdrawn as a strand of twisted spun yarn in a known way through a yarn channel (not shown) then to be taken up on a bobbin for forming a yarn package.
The inner peripheral wall of the space in which the combing roller 6 is rotatably disposed has an opening 8 through which part of the circumferential surface of the rotating combing roller 6 may be exposed to a trash discharging chamber 9 formed adjacently to the combing roller 6 in the spinning unit 1. Trash or foreign matters 7 contained in the sliver 3, including leaf pieces, neps, short fibers and other impurities, are removed from the fibers separated by the combing roller 6 and discharged through this opening 8 into the trash discharging chamber 9.
The trash discharging chamber 9 has at one end thereof an air inlet 9a and at the other opposite end thereof an exit 9b connected to an end of a trash pipe 12 through which the trash 7 is delivered from the chamber 9. The trash pipe 12 is connected at the other end thereof to a trash transporting duct 13 which is shared in common by a plurality of other similar trash pipes coming out from other spinning units of an open-end spinning frame, and which is connected to a trash collecting chamber 15 via a blower 14. In order to develop strong vacuum in the trash discharging chamber 9 for aiding in removal and delivery of the impurities 7, the air inlet 9a of the trash discharging chamber 9 is formed by an opening with such a small diameter that the chamber 9 is of a substantially closed construction. The impurities 7 removed from the fibers and discharged through the opening 8 into the trash discharging chamber 9 is drawn into the trash pipe 12 under the influence of a flow of air current caused by vacuum which is created by the blower 14 and then transported through the duct 13 up to the trash collecting chamber 15, where the impurities thus transported are collected and stored with impurities delivered from other spinning units.
In the trash removing apparatus of the foregoing structure in an open-end spinning frame, wherein its trash discharging chamber 9 has a limited capacity and its air inlet hole 9a is of nearly closed configuration, the trash 7 is placed under the influence not only of the suction by the blower 14, but also of the suction effect caused by rotation of the spinning rotor 11, with the result that various inconveniences or drawbacks are invited.
As described in the above, the trash 7 removed from the fibers and discharged into the trash discharging chamber 9 is carried therefrom into the trash pipe 12 by a current of air stream developed in the chamber. Since it is desirable that a relatively strong suction should be developed in the trash discharging chamber 9 for delivery of the refuses 7, the opening of the air inlet 9a of the trash discharging chamber 9 is restricted. Therefore, the trash discharging chamber 9 is susceptible to the influence of a suction due to the vacuum created by the high-speed rotation of the spinning rotor 11; i.e., the vacuum developed in the trash discharging chamber 9 aids the vacuum created due to the rotation of the spinning rotor 11 in exerting its suction effect on the trash discharging chamber 9. The result is that part of the trash once removed from the fibers and discharged through the opening 8 may be caught by such suction and drawn with the fibers into the spinning rotor 11 thereby to be deposited in the rotor and therefore included in the resulting spun yarn. Furthermore, because the capacity or space of the trash discharging chamber 9 is relatively small, there is a tendency of the impurities 7 discharged through the opening 8 impinging against any of the inner walls defining the trash discharging chamber 9 and then being rebounded, so that part of the impurities 7 thus rebounded from the wall may be caught and entrained by a flow of air stream caused by the abovesaid suction effect due to the rotation of the spinning rotor 11, and therefore introduced into the rotor together with fibers. In addition, formation of a so-called air curtain adjacently to the opening 8 due to strong air streams within the trash discharging chamber 9 makes it further difficult for the impurities 7 to be removed efficiently, but allowing part of them to be placed under the influence of the suction which acts in a direction opposite to discharging of the trash 7.
One solution to avoid such phenomena would be to increase the velocity of the air flow by the blower 14 in the trash discharging chamber 9. However, such air flow would peel out not only the foreign matters 7 but also usable long fibers off the surface of the combing roller 6 and draw them toward the trash pipe 12, thus resulting in a decrease of yarn yield. Furthermore, an increase in the velocity of the air flow may cause the air outlet 9b of the trash discharging chamber 9 to be clogged with the trash 7 and fibers, thereby blocking the passage of the trash pipe 12.